The main objective of this project is the synthesis of compound libraries based on enantiomerically pure, stereochemically well-defined, novel, versatile, and interesting molecular scaffolds that are derived from or inspired by natural products and privileged structures. The specific aims of this project are: 1. Prepare a demonstration library based on the eight-membered lactone natural product and powerful antitumor agent octalactin A via ring-closing metathesis (RCM) chemistry and evaluate the analogues for cytotoxic activity against human cancer cell lines. 2. Develop a new class of ionic norbornenyl linkers for combinatorial chemistry. 3. Preparation of trienomycin A analogues by combinatorial methods using both solid- and solution-phase technologies. 4. Utilization of polymer-supported phosphonium salts, olefin cross-metathesis, oligomeric chiral auxiliaries and PEG-supported dioxolanes during the construction of the macrocyclic core of trienomycin A. 5. Development of novel chemistry to prepare unique nitrogen-containing scaffolds. 6. Development of novel traceless linker methodology for solid phase asymmetric synthesis.